In mobile radio networks operating according to the GSM standard, communication by means of short messages on the basis of the standard provided therefore has become successfully established in addition to voice communication, while also providing cost advantages. In addition to the cost advantages, message transmission by SMS (short message service) also has advantages in specific applications, where reception and sending of an SMS can be realized without an acoustic annoyance for the environment. Furthermore, the transmission of short messages also affords additional expression and psychological articulation possibilities compared with voice communication.
SMS is a point-to-point short message service which is realized in the context of the GSM protocol architecture at the signaling level. It comprises the transport of packet-oriented useful data from and to mobile stations. The short • messages are always transported via a short message service center (SM SC) in store-and-forward operation. The service center accepts the short messages, which are typically no more than 160 characters long, from a mobile station as telecommunication terminal and forwards them to a second telecommunication terminal—a further mobile station or else a fax unit or the like.
The GSM standard defines a specific protocol architecture for realizing this service. This architecture is defined in the ETSI specifications and is described in the literature (cf. for instance, J. Eberspacher, H. J. Vogel: “GSM Global System for mobile communication”, Stuttgart, 1997), so that a more detailed description can be dispensed with here and reference may be made to the appended list of standards/documents.
In the existing public line-connected telephone networks, such a transmission of short messages between normal telecommunication terminals (e.g. telephones) is not possible at the present time.
GB 2 298 339 A discloses a method for transmission of short messages between a short message service center and a DECT cordless telephone, comprising a fixed station and a mobile part, in which the short message is transmitted from the service center to the fixed station via a separate connection specific to the service center operator, which connection is realized e.g. as an x.25 network, in accordance with an SMS-specific protocol.
U.S. Pat. No. 5,815,506 discloses a satellite communication system by means of which a short message generated by a fixed network subscriber is transmitted to a mobile radio subscriber in accordance with an SMS-specific protocol. For this purpose, the short message is firstly transmitted from the fixed network subscriber via a PSTN network to a short message server. From there a short message passes via a local satellite ground station, a satellite and a mobile radio station to the mobile radio subscriber. Signaling outside the voice or useful data band, so-called out-of-band signaling, is used for the short message transmission between the fixed network subscriber and the mobile radio subscriber. Message volumes of up to a maximum of 16 Kbytes can be transmitted with this type of short message transmission. A “DIAL UP” modem and also a DTMF tone identification are available in the PSTN network for this type of transmission.